Long-term heroin users are among the hardest addicts to treat. They lead chaotic lives, often robbing and stealing to fund their habits. According to official figures, 10 per cent of drug addicts commit 75 per cent of the acquisitive crimes in the Britain. But the number of offences committed by the heroin addicts taking part in the shooting gallery scheme fell from an average of 40 each per month before they were admitted to "about half a dozen a month" after six months of intensive therapy. Instead of buying street heroin every day, the 150 volunteers are now buying it only four or five times a month on average – while a third of them have completely stopped "scoring" the drug on the streets.

Professor Strang, head of the National Addiction Centre at the Maudsley Hospital: "This is genuinely exciting news. These are people with a juggernaut-sized heroin problem and I really didn't know whether we could turn it around. We have succeeded with people who looked as if their problem was unturnable, and we have done it in six months."

Mafia compete against each other, making drug supplies more and more potent to keep their customers. Legalisation would break that cycle. If currently illegal drugs were legalised, they could be regulated in the same way other damaging substances -- tobacco and alcohol -- are. Users could also purchase from places where they would be sure drugs had not been tainted with other substances.